The invention relates to an electronic circuit arrangement for serial data transfer with a transmitting device with several bit-parallel input information units, a serial data transfer line and a receiving device via which the transferred data are correspondingly converted into bit-parallel output information units to drive control elements or logic circuits, with the data to be transferred forming on the data transfer line a data word composed of a start pulse, several information units corresponding to the number of bit-parallel input information units forming a data block, and a defined data pause.
The conversion of bit-parallel signals into bit-serial signals and the reverse of this procedure are necessities in teleprocessing and teleprinter communications. This conversion is, however, also used by local computer networks if, for example, a terminal is installed in a different wing of the building than the central processing unit.
With microprocessors, separate peripheral components, so-called Universal Synchronous/Asynchronous Receiver/Transmitter (USART) components, can be used for this conversion. Software solutions are, however, also known wherein standard I/O ports are used.
In the transmission of, for example, teleprinter signals, the data to be transferred are defined by the ASCII Code (American Standard Code for Information Interchange) and the levels on the transmission lines are specially standardized, as, for example, in the case of the voltage interface RS 232 (CCITT recommendation V24).
For certain applications such as, for example, in motor-vehicle electronics, a microprocessor solution for serial data transfer involves too much expenditure if, for example, switch positions for various consumers are to be converted as parallel input information units into a serial data word in order to drive bit-parallel relays as control elements corresponding to the switch positions on the receiver side.
With microprocessors, the bit-parallel input information units are extended via the I/O ports with corresponding addressing and software-related programming expenditure.